A variety of sophisticated equipment has been developed in order to provide for high volume production of integrated circuits. Obviously, it is the objective of such equipment to reduce or eliminate as many of the manual tasks within an operating phase as is practically possible. In addition thereto, automated equipment and materials used therein have been developed in order to reduce the number of steps employed within each phase of the process.
In one conventional technique, a bonding method employing a film-like chip carrier has been successfully developed in which a relatively thin metallic foil, which ultimately serves as the chip leads, is preferably releasably bonded to a plastic film which serves as the chip lead carrier. Both the foil and the film are treated so as to form the lead configuration (in the case of the foil) and form the substrate for supporting the lead frame (in the case of the film), which carrier thereby resembles the lead pattern. Sprockets are also formed in the carrier tape edges to permit high-speed automated handling of the lead frames (which are quite small and quite fragile) in much the same fashion as the handling or advancement of photographic film.
The chips to be mounted to each lead frame are typically bonded to the inner ends of the leads, usually by thermocompression bonding. Alternatively, ultrasonics reflow soldering, welding, or eutectic bonding techniques may be employed.
Once the above automated operation is completed, the chips, after being mounted to the chip lead frames, undergo an automated operation typically referred to as outer lead bonding, in order to connect the film carrier beam to a more rugged DIP (dual in-line package) lead frame, hybrid substrate or a printed circuit board which may be of either the rigid or flexible type. In the lead frame operation, the frame carrying a chip is typically punched away from the tape, brought into alignment with the lead frame and then bonded, preferably through thermocompression bonding, to the lead frame, the lead frames also preferably being arranged in a continuous tape-like fashion to facilitate automated handling. Thereafter, the lead frames of each completed assembly are severed from one another and secured to DIPs (also by thermocompression bonding, for example). Most applications at present utilize injection molded plastic packages which do not provide a hermetic seal for the DIPs.
It can also be seen from the foregoing description that at least two separate bonding steps are required to complete the mounting of an integrated circuit chip within a DIP. In addition, an intermediate conductor structure is required to provide connections between the integrated circuit and the ends of a DIP, namely the conductive foil lead pattern whose inner ends are connected to the chip; and the DIP lead frame whose inner ends are connected to the outer ends of the chip lead frame.